Warm inflation
(WI) [1]}, [2]}, [3]} is an
alternative dynamical realization for conventional cold inflation
(CI) [4]}, [5]}, [6]}, [7]}, [8]}
during which the inflaton field dissipates its vacuum energy into an
ambient radiation bath, thus eliminating the necessity of a
post-inflationary reheating process [9]} and leading
into different possibilities for a graceful exit
mechanism [10]}. Such a non-equilibrium dissipative
particle production process acts to slow the motion of the inflaton
field, allowing the embedding of steeper potentials in the WI context
and helping in solving, for example, the so-called
\(\eta \) -problem [11]}, [12]}, [13]}. In
WI the thermal fluctuations play the dominant role in the formation of
the seeds for the Large Scale Structure (LSS) by producing a quasi
scale-invariant spectrum of primordial curvature perturbations. At the
same time, the shape of the produced spectrum depends on the field
content of the model, leading to signatures able to make it
distinguishable from the one produced in
CI [14]}, [15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]}, [22]}.
Furthermore, the rich dynamics of WI allows it to address/alleviate
some of long-lasting problems related to the (post-)inflationary phase
in the CI
scenarios [23]}, [24]}, [25]}, [26]}, [27]}, [28]}, [29]}, [30]}, [31]}, [32]}, [33]}, [34]}
(see also
Refs. [35]}, [36]}, [37]} for
related work).
